Estimation of Heat Losses from Modified Cavity Mono-tube Boiler Receiver of Solar Parabolic Dish for Steam Generation

In this article, a 3-D numerical investigation is carried out to estimate heat losses from solar parabolic dish with modified cavity receiver used for three different steam generation conditions viz. sub-cooled, saturated, superheated steam. The effect of inclination of the receiver, operating temperature, emissivity of the cavity cover, insulation thickness on the total heat loss from the modified cavity receiver has been investigated. The variable wall temperature boundary conditions and insulation thicknesses are applied to match the actual conditions. The results show that the convection heat losses are higher at 0° inclination and found to be 400 to 500 W for superheated steam generation; 300 to 425 W for saturated steam generation and 50 to 125W for sub-cooled steam. The radiation heat losses remain constant for all inclinations and vary with the temperature. Nusselt number correlations have been proposed based on the numerical analysis. The present model can be used to predict total heat losses from the modified cavity receiver under all conditions more accurately.